In the second part, [i]Trattato dell'architettura[/i] (tractate on architecture) Pacioli discusses in 20 chapters the ideas of Vitruvius on mathematics in architecture. [br]Pacioli compares the proportions of the human body with architecture, starting from examples in Greek and Roman architecture.[br][br]In this part there's a detailed drawing of a human heads.[br][list][*]Pacioli starts from an equilateral triangle, not coincidentally the first problem in Euclides' book.[/*][*]This triangle is fitted into a rectangle.[/*][*]In this rectangle a grid is drawn so that eyebrows, nose and lips coincide with the Vitruvian proportions. [/*][/list]Now every distance can be calculated out of the ratio of the base(b) and height (h) of the triangle.

In this drawing [math]\sqrt{3}[/math] is the only root appearing in calculations.[br]There isn't any question of [math]\varphi=\frac{\sqrt{5}-1}{2}[/math] nor [math]\Phi=\frac{\sqrt{5}+2}{2}[/math]. More, Pacioli didn't even know the term [i]golden section[/i].[br]In other words: Pacioli is bad source to illustrate the use of the golden section in the human body or in architecture.